Downhole under-reamer tool

摘要

A downhole tool comprises a body having slots communicating the outside of the body with the body through-bore. A sleeve actuator and mandrel are selectively axially slidable. The actuator has flanges extending into the slots. The flanges have ribs on their sides that are inclined at an acute angle to the longitudinal axis of the tool. Hollow bars are slidable in the slots and they have channels inside corresponding with, and engaged in, the ribs of the flanges. The sleeve actuator slides in the body between a tool actuated position and a tool deactuated position. The mandrel is selectively axially slidable between a tool actuated position, an interlock position and a sleeve-lock position. A lock ball locks the sleeve actuator with respect to the body in the tool deactuated position and while the mandrel is between the interlock and sleeve-lock positions. The lock ball also locks the sleeve actuator with respect to the mandrel while the mandrel is between said interlock and tool actuated positions.